Alcohol dehydrogenases that react with secondary alcohol compounds, such as 2-butanol, are useful enzymes in syntheses of optically active alcohol compounds through stereoselective reduction reaction of carbonyl compounds or syntheses of optically active secondary alcohol compounds through stereoselective oxidation reaction of racemates of secondary alcohols.
Among alcohol dehydrogenases yielded by microorganisms, there are many reports on alcohol dehydrogenases that require nicotinamide adenine dinucleotide (hereafter to be abbreviated as “NAD+”) as a coenzyme, and oxidize 2-butanol. There are, however, few reports on alcohol dehydrogenases that preferentially oxidize (S)-2-butanol in comparison with (R)-2-butanol and whose corresponding structural gene (a DNA coding for an enzyme) has been acquired.
As such an alcohol dehydrogenase, enzymes derived from Gordonia sp. strain TY-5, and Candida parapsilosis IFO 1396 strain have been known.
Among the above enzymes, ADH1, which is an enzyme derived from Gordonia sp. strain TY-5, is characterized in that it has a molecular weight of approximately 35,000 as determined by SDS-polyacrylamide electrophoresis, and has an optimum temperature of 30° C. and an optimum pH of 10 in oxidation of 2-propanol. ADH3, which is an enzyme derived from the same strain, is characterized in that it has a molecular weight of approximately 58,000 as determined by SDS-polyacrylamide electrophoresis, and has an optimum temperature of 60° C. and an optimum pH of 10 in oxidation of 2-propanol (See the Patent Document 1 listed below).
An enzyme derived from Candida parapsilosis IFO 1396 strain is characterized in that it has a molecular weight of approximately 40,000 as determined by SDS-polyacrylamide electrophoresis, a stable pH range of 8.0 to 10.0, and an appropriate temperature range for action in oxidation of (S)-2-buthanol is 25° C. to 55° C. This enzyme has a character that activity of the enzyme is inhibited by 2-mercaptoethanol or dithiothreitol, whereas it is not inhibited by ethylenediaminetetraacetic acid (See the Patent Document 2 listed below).
Thus, there are few alcohol dehydrogenases that preferentially oxidize (S)-2-butanol in comparison with (R)-2-butanol and whose corresponding structural gene (a DNA coding for an enzyme) has been acquired. In view of the state of the art, acquisition of novel enzymes or their corresponding structural gene has been desired. If the structural gene of such enzymes is acquired, the enzyme can be produced through a genetic engineering technique in a large amount, and thereby enables to establish a process that can produce useful compounds, for example, optically active alcohols, with the enzyme in a remarkably efficient manner.    Patent Document 1:JP-A-2005-102511    Patent Document 2:JP-B-3574682